Heat-resisting alloy



' valve heads, and valve guides.

Patented Aug. 7, 1928.

UNITED STATES ALFRED L. BOEGEHOLD, OF RESEARCH CORPORATION,

PATENT OFFICE.

HEAT-RESISTING ALLOY.

l lo Drawing. Application filed June 6,

This invention relates to an alloy containing a preponderance of iron, which is as readily machinable as grey iron, and will not scale, warp and grow substantially, as do ordinary iron or steel, when subjected to high'temperatures.

The alloy which is the subject of this application is intended particularly for use in internal combustion engines for parts that become highly heated in use, such as It is, however, well adapted as material for other articles subject to high heat.

The preferred composition of the alloy is as follows 1 Carbon 2.60%, silicon 2.00%, nickel 4.00%, aluminum 6.00%, the remainder iron.

The preferred composition may be departed from within the range of ingredients here stated without substantial deterioration of the desired properties.

Carbon may vary between 2.40 and 2.80%, silicon between 1.7 5 and 2.25%, nickel between 3.7 5 and 4.25%, aluminum between 5.75 and 6.25%.

In the analysis the following named elements may occur as impurities without injurious effect provided'they are not present tolerated in amounts not over not over 0.12% and manganese .80%.

This alloy may from .40 to be made by melting iron associated with the requisite. carbon and in excessive amounts: phosphorous may be 0.50%, sulphur- 1927. Serial No. 197,016.

silicon content in an electric furnace, then adding to the molten iron the necessary quantity of nickel. Or the iron and nickel may be placed together in a pot and melted at the same time. Ferro silicon may be added if silicon content in the iron is too low. lVhen the mixture is thoroughly melted and mixed and has attained high fluidity it may be tapped into a ladle in which the required weight of aluminum has been placed. The temperature then rises to the Thermit reaction and considerable dross comes to the surface. If aluminum be melted with the iron and nickel it appears to precipitate the carbon, thus rendering it extremely diiiicult to control the analysis. The molten alloy mixture should be poured as soon as possible after the reaction is com plete since it is quite sluggish and sets quickly.

The castings are quite hard as-taken from the mold and should be annealed about two hours at approximately 1450 F. after which they may be machined readily.

I claim:

1. A heat resistant alloy composed of iron 2.40 to 2.80% carbon, 1.75 to 2.25% silicon, 3.75 to 4.25% nickel, and 5.75 to 6.25% aluminum.

2. A heat resistant alloy composed of iron, substantially 2.60% carbon, 2.00% silicon, 4.00% nickel and 6.00% aluminum. In testimony whereof I aflix my signature.

, ALFRED L; BOEGEHOLD. 

